venting soil stack through a wall?

[redhexagonal]

I have a soil stack in my attic that I discovered is open. I fitted a Durgo AAV but this caused gases to build up and leak out from the bath p trap. I took the Durgo off and the smell stopped. So I'm thinking I need to vent the soil stack externally. My roof is asymmetrical, it rises to the top of a wall, and there are a couple of vents in the wall, one goes through the attic to the bathroom extractor and one is unused. Would it be OK to connect the soil stack to the unused one? Its only about 15cm from the bathroom vent, and about 2 or 3m from the neighbours bathroom window.

 

[Exedon]

Vent must terminate 900mm above any opening into a building within
3 meters of vent .
Section 1.31 Document H building regulations.

 

[redhexagonal]

Vent must terminate 900mm above any opening into a building within
3 meters of vent .
Section 1.31 Document H building regulations.

does the bathroom vent count as an opening?

 

[Exedon]

Yes any opening into a building.